Vertical Transmission of Group B Streptococcus, Prevalence, Associated Factors, and Antimicrobial Susceptibility Profile among Newborns Delivered at Health Facilities in Jigjiga City, Ethiopia

Background Group B Streptococcus (GBS) colonizes the rectovaginal area of women and vertically transmitted to neonates. This bacterium has been linked to severe neonatal complications including pneumonia, septicemia, and meningitis. GBS shows an increased resistance to commonly used antibiotics. Thus, we assessed the vertical transmission, contributing factors, and antimicrobial resistance patterns of GBS among newborns delivered at selected Hospitals in Jigjiga City. Methods Hospital-based cross-sectional study was conducted from 1st June 2022 to 30th April 2023. A total of 849 pregnant women admitted to delivery wards from two hospitals were screened for GBS colonization. Subsequently, 162 GBS-colonized pregnant women and their newborn babies were included. A semistructured questionnaire and a review of medical records were used to collect the sociodemographic and clinical characteristics of the study participants. Trained nurses collected swab samples from the vaginal-rectal area of pregnant women and the nasal, ear canal, and umbilical areas of newborn babies. Samples were inoculated on Todd Hewitt broth media supplemented with gentamycin and nalidixic acid and then subcultured on blood agar. Colony characteristics, Gram stain, and catalase test were used for identification. All gram-positive cocci, B-hemolytic, and catalase-negative isolates were further identified using Christie–Atkins–Munch–Petersen and a bacitracin test. The modified Kirby-Bauer disk diffusion method was used for antimicrobial susceptibility testing. Data were analyzed using SPSS version 26. Logistic regression analysis was used to determine the factors associated with vertical transmission of GBS, and statistical significance was set at p values <0.05. Result The overall vertical transmission rate was 41.4% (67/162). History of preterm labor (Adjusted odds ratio (AOR) = 2.25; 95% CI: 1.11, 4.59), history of urinary tract infection (UTI) at current pregnancy (AOR = 2.25; 95% CI: 1.11, 4.59), and prolonged rupture of membranes greater than 18 hours (AOR = 2.23; 95% CI: 1.13, 4.4) were significantly associated with vertical transmission of GBS from previously colonized mothers to their newborn babies. Regarding GBS antibiotic susceptibility profile, a significant degree of resistance was observed to penicillin (29.9%), tetracycline (22.4%), ampicillin (20.9%), and clindamycin (19.4%). Conclusion Our study documented a high prevalence of vertical transmission rate of GBS from pregnant women to their babies, with an overall transmission rate of 41.4%. The study identified the presence of antimicrobial-resistant GBS to penicillin, ampicillin, clindamycin, ciprofloxacin, and chloramphenicol. The organism was susceptible to vancomycin, followed by azithromycin, ceftriaxone, and erythromycin. Our study also reported MDR at 13.4%. Based on our findings, there is a need for antenatal culture-based GBS screening, maternal vaccination, and large-scale epidemiological and serotype identification studies to be put into practice in the study area.


Introduction
Group B Streptococcus (GBS), also known as Streptococcus agalactiae, is facultative anaerobic, encapsulated, betahemolytic, and Gram-positive bacteria [1].It is catalase negative, bacitracin resistant, positive in the Christie--Atkins-Munch-Peterson (CAMP) test, and forms large white mucoid colonies on blood agar plates [2].GBS colonizes the gastrointestinal and vaginal tracts of one third of pregnant women asymptomatically, as part of the normal fora [3].Multiplication of these bacteria around the vaginal area can cause maternal morbidity during pregnancy [4].Newborns from GBS-positive pregnant women are at substantial risk of infection [5].About 50-75% of infants born to GBS-positive mothers become colonized at birth [6].Microorganisms are transmitted vertically from the maternal vaginal or anorectally colonized mucosa throughout labor or in utero [7].As a result, infants may develop colonization of their skin, oral cavity, nasopharynx, vagina, and various mucosal surfaces [8].
It has been reported that GBS is the principal cause of neonatal sepsis, meningitis, and pneumonia which are attributed to infant mortality [9].Neonatal diseases caused by GBS are categorized as early-onset disease (EOD) and lateonset disease (LOD) [2].Te primary risk factor for EOD is rectovaginal colonization in pregnant women with GBS before or during delivery, which occurs in the frst week of life (0-6 days) with pneumonia or respiratory distress, commonly advancing to sepsis [4].
Newborns with LOD often range in age from the 7th day to the 89th day.Tey typically appear with bacteremia and have a high meningitis complication rate.Tey arise from maternal, nosocomial, or community sources [10].
GBS is the leading cause of early invasive infection in newborns worldwide [11].Tis bacterium has been associated with 205,000 EOD cases, 3.5 million preterm deliveries, 57,000 stillbirths, 90,000 infant deaths, and more than 10,000 new cases of neurodevelopmental abnormalities per year globally [11].Te fatality rate for infants with EOD disease is estimated to be 4-6% [12].Moreover, surviving infants may experience long-term disabilities including hearing loss, vision loss, and mental retardation [13].Most severe neonatal cases, stillbirths, and infant fatalities occur in Africa [14].
Administration of IAP treatment with penicillin or amoxicillin to GBS-colonized pregnant women, pregnant women with risk factors, and pregnant women with unknown colonization status is considered the most efective approach for preventing EOD in newborns [8].Penicillin is still considered the frst-choice antibiotic for IAP to prevent EOD and to treat GBS disease [21].However, resistance to penicillin and fuoroquinolones has recently been observed [22].Over the last two decades, GBS has been increasingly resistant to a variety of antibiotics, including macrolides (such as erythromycin) and lincosamides (such as clindamycin), from <5% to common resistance of 20-30% [4,23].Antimicrobial resistance is difcult to treat and poses a serious health risk, causing a sharp increase in GBS infections in newborns.One issue prompting this concern is the increased prophylactic use of antibiotics, without appropriate bacterial culture and screening.Terefore, the antimicrobial resistance of GBS to diferent antibiotics is a major issue worldwide [24].Furthermore, most developing countries like Ethiopia do not have clear guidelines for the prevention of vertical transmission of GBS from GBS-positive mother to neonates due to limited information regarding it.Tus, the current study aimed to investigate the vertical transmission rate, associated factors, and antimicrobial resistance patterns of GBS among newborns delivered at selected health facilities in Jigjiga city.
Prevention techniques, including universal antenatal GBS screening, identifcation of risk factors, and antibiotic prophylaxis at delivery, have been capable of signifcantly limiting the disease [15].

Study Design, Area, and Period.
A hospital-based crosssectional study was conducted from June 01, 2022, to April 30, 2023, at two selected Hospitals in Jigjiga city, the administrative city of the Somali regional state.Te city is located 636 km southeast of Addis Ababa, Ethiopia's capital city.According to data from the Central Statistical Agency in 2015, the estimated total population of Jigjiga City is 304,000 [25].At the time of data collection, three hospitals and four health centers ofered delivery services in Jigjiga.Te largest client loads for delivery services were used to determine the selection of two hospitals: Karamara General Hospital (KGH) and Jigjiga University Sheik Hassen Yabere Referral Hospital (JUSHYRH).

Population.
All pregnant women admitted to the delivery rooms and their newborn babies at JUSHYRH and KGH were the source population of the study.Te Study population consisted of newborn babies delivered from GBS-colonized pregnant women.

Eligibility Criteria.
All GBS-colonized pregnant women admitted to the labor and delivery rooms at JUSHYRH and KGH during the data collection period and their newborn babies were included in this study.Pregnant women who used vaginal cream, lubricants, traditional sterilizers (vinegar), and antibiotics in the last two weeks before data collection were excluded from the study since the where N � the desired sample size, z � standard normal distribution value at 95% CI, d the acceptable margin of error, and p the proportion of GBS vertical transmission from a previous study.Te calculated sample size was allocated proportionally to each selected hospital based on the estimated number of pregnant women visiting the delivery ward in the three data collection months: 720 in JUSHYRH and 530 in KGH.Te number of samples in each selected hospital was determined by the proportional allocation method using the following formula: where n is the sample size, N1 is the average number of pregnant women attending the delivery ward in each hospital, Nt is the total number of pregnant women attending the delivery ward in both hospitals, and nt is the determined sample size.Terefore, 162 GBS-colonized pregnant women (93 from JUSHYRH and 69 from KGH) admitted to the delivery ward and their newborn babies were included in the study.Participants were recruited from the study population using a convenient sampling technique.

Data Collection.
A semistructured questionnaire with a review of medical records was used to collect the sociodemographic, obstetric, and clinical characteristics of the study participants to investigate the factors associated with vertical transmission of GBS.Te questionnaire was developed based on the WHO and Center for Disease Control and Prevention (CDC) guidelines and referring related literatures [26,27].

Specimen Collection and Bacteriological Procedures.
Vaginal rectal swabs were collected from pregnant women admitted to the labor and delivery room by brushing the lower vagina and rectum with sterile cotton swabs by trained nurses following universal precautions [28][29][30].Swabs were also collected from the nasal area, ear canal, and umbilical areas of newborns within 30 min of birth, following the standards of the American Society for Microbiology (ASM).Bacteriological analysis was performed following the methods described by the CDC, American College of Obstetrician's Gynecologists, and ASM [30,31].Samples were inoculated in Todd Hewitt broth media supplemented with gentamycin (8 μg/ml) and nalidixic acid (15 μg/ml) and incubated at 37 °C with 5% CO 2 for 24 h.Ten, they were subcultured on blood agar plates and incubated at 37 °C with 5% CO 2 for 24 h-48 h.Colony characteristics, Gram staining, and catalase tests were used for presumptive identifcation.All Gram-positive cocci and B-hemolytic and catalase-negative isolates were further identifed using CAMP and bacitracin tests.Te CAMP test was used to diferentiate CAMP-positive GBS from other beta-hemolytic Streptococci while bacitracin test was used to distinguish GBS from group A streptococci, which are both B-hemolytic [28,32].
2.9.Data Analysis.Te data were analyzed using SPSS V26.Frequency tables, graphs, and other statistical summary measures were used to summarize the results.Bivariate logistic regression analysis was used to assess the potential factors contributing to vertical transmission.Variables with p − value ≤ 0.25 were entered into the multivariate logistic regression analysis.Crude odds ratios (COR) and adjusted odd ratios (AOR) were used to determine the strength of the association.Statistical signifcance was set at p values <0.05.

2.10
. Data Quality Control.Te questionnaire was pretested and training was provided to the data collectors before data collection.Standard operating procedures (SOPs) were followed for sample collection, transportation, and bacteriological processing.Any physical changes (growth of microorganisms) and expiration dates were checked before using the reagents and culture media.Te international control bacterial strains Streptococcus agalactiae (ATCC 27956), Staphylococcus aureus (ATCC 24923), Streptococcus pyogenes (ATCC 19615), and Escherichia coli (ATCC 25922) were used as quality controls for the culture and antimicrobial susceptibility test (AST) [34,35].

Operational Defnitions
(i) Vertical transmission: transmission of the pathogen from mother to neonate during delivery (ii) GBS colonization: a condition by which carrying GBS in/on bodies with growth and multiplication without showing tissue invasion or damage [35].(iii) Early-onset disease: diseases that appear from birth to 6th completed days [4].(iv) Late-onset disease: diseases that appear in infants between the 1st week and 89 days of age [4].(v) MDR: a condition by which an organism is resistant to three and more class of antibiotics [33].

Sociodemographic, Obstetric, and Clinical Characteristics of Study Participants.
A total of 849 pregnant women admitted to the delivery ward from two hospitals were screened for GBS colonization; 478 pregnant women were from JUSHYRH, while the remaining 371 were from KGH.Of these, 162 GBS-colonized mothers (93 from JUSHYRH and 69 from KGH) and their newborns were recruited for the study.Majority of GBS-colonized mothers were married (67.3%), urban residents (72.8%), and aged greater than 25 years (75.3%).Moreover, most of the study participants cannot read and write (38.3%), followed by primary level of education (26.5%) and secondary level of education (21%) (Table 1).

Vertical Transmission and Associated Factors of Group B
Streptococcus from Mothers to Newborns.A total of 162 GBScolonized pregnant women and their paired babies were included in this study.Te overall vertical transmission rate was 67 (41.4%).All newborns colonized by this bacterium descended from previously colonized mothers (Figure 1).
Te results of bivariable and multivariable logistic regression showed that a history of preterm labor (<37 weeks), history of UTI at current pregnancy, and prolonged rupture of membranes greater than 18 hours were signifcantly associated with vertical transmission of GBS from previously colonized mothers to their newborns.Mothers with a history of preterm labor (<37 weeks) were 2.25 times more likely to transmit GBS vertically to their newborns during delivery (AOR � 2.25; 95% CI: 1.11, 4.59).Whereas mothers who had a history of UTI at current pregnancy were 2.37 times more likely to transmit GBS vertically to their newborns during delivery (AOR � 2.37; 95% CI: 1.19, 4.71).In addition, mothers who had prolonged rupture of membrane greater than eighteen-hour were 2.23 times more likely to transmit GBS vertically to their newborns during delivery (AOR � 2.23; 95% CI: 1.13, 4.4) (Table 3).

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Discussion
Vertical transmission of GBS is a serious clinical and public health concern [36].Tis bacterium is associated with EOD, preterm delivery, stillbirth, infant death, and neurodevelopmental abnormalities.Te most severe neonatal cases, stillbirths, and infant fatalities occur in Africa [14,37,38].
In this study, the overall vertical transmission rate of GBS was 41.4% (95% CI: 33.7, 49.4%).Tis fnding is in line with studies in Ethiopia which were conducted by Yadeta et al. [15] and Fantahun et al. [19], who reported a 45.02% and 47.6% rate of vertical transmission, respectively.However, this fnding is higher compared to a study conducted by Le Doare et al. in Germany (11.2%) [9], Chen et al. in China (0.7%) [39], and Shah et al. in India (3.23%) [40].Furthermore, the fndings were higher compared to those in Africa, which were reported by Matee et al. in Kenya (8.9%) [41], Alemseged et al. in Ethiopia (11.9%) [42], and Ali et al. in Ethiopia (7.4%) [43].A possible reason for this diference might be due to variations in study design, sample size, lifestyle, and prevalence of bacteria in the populations.On the other hand, the vertical transmission rate of GBS in this study was lower compared with studies conducted by Gizachew et al. [18] and Ali et al. [5] in Ethiopia, who reported 63.3% and 59.1% of vertical transmission rates, respectively.A possible reason for this diference might be variations in the study design, sample size, and lifestyle.
Our study reports a higher level of resistance of GBS for penicillin and tetracycline which was consistent with the studies done in high resistance in fve subregions of Africa, Gondar, and Jigjiga [28,48,49].
Tis moderate antibiotic resistance found in our study area could be explained by a variety of factors, such as the excessive and improper use of antibiotics in the study area, which lacks regular antimicrobial susceptibility testing facilities and loose regulatory practices.Te majority of the antimicrobials on this list can be bought and used without     International Journal of Microbiology membranes greater than 18 h (AOR � 2.23; 95% CI: 1.13, 4.4) showed a statistically signifcant association the vertical transmission of GBS.GBS generates extracellular membrane vesicles via virulence factors and toxins.Tis leads to extraplacental membrane thinning, collagen breakdown, and preterm birth [51].Te cytokeratin network in the amniotic epithelium becomes dysfunctional because of GBS infection of the choriodecidua, which weakens the membrane and leads to early membrane rupture.Membrane rupture increases the risk of infection because it leaves the fetus and amniotic fuid, which is a favorable environment for bacterial growth [52].As GBS is one of the causative agents of UTI, mothers with UTI have a higher risk of vertical transmission of GBS [17].Tis fnding is supported by the studies conducted by Kim et

Conclusion and Recommendation
Te current study revealed a high prevalence of vertical transmission rate of GBS from pregnant women to their babies, with an overall transmission rate of 41.4%.History of preterm labor (<37 weeks), history of UTI at current pregnancy, and prolonged rupture of membranes greater than 18 h were signifcantly associated with vertical transmission of GBS from previously colonized mothers to their newborns.Moreover, the study identifed that GBS has increased antimicrobial resistance to penicillin and high susceptibility to vancomycin compared with other drugs.Tese fndings suggest the need for antenatal culture-based GBS screening, maternal vaccination, risk factor-based interventions, and regular follow-up of drug resistance patterns to ensure proper treatment.Large-scale epidemiological studies with larger sample sizes are recommended.

Limitation of the Study. Serotyping and molecular tests
were not performed to further characterize the identifed GBS isolates.Te fndings may not be generalizable to the entire community as the study was conducted in health facilities.
this research project was obtained from Jigjiga University Research Directorate.

Figure 1 :
Figure 1: Proportion of GBS vertical transmission from mothers to newborns during delivery at JUSHYRH and KGH.

Figure 2 :
Figure 2: AST profle of GBS isolated from newborns at delivery at JUSHYRH and KGH.

Table 3 :
Bivariate and multivariate analysis of factors related with vertical transmission among study participants attending JUSHYRH and KGH, Jigjiga, Ethiopia.

Table 4 :
Antibiotic susceptibility profle of GBS isolated from newborns at delivery at JUSHYRH and KGH, Jigjiga, Ethiopia.